NASA said Friday it had selected SpaceX, the operator of Falcon 9 rockets,to take over launch pad 39A, a mothballed former Apollo and space shuttle pad that the agency no longer needs and can't afford to maintain.

SpaceX, of Hawthorne, Calif., has contracts to launch cargo to the International Space Station and numerous commercial satellites, and is competing to launch NASA astronauts as well as high-value national security and science satellites.

NASA made the decision immediately after the U.S. Government Accountability Office's rejection on Thursday of a bid protest filed by Blue Origin, which had put the selection process on hold.

"Permitting use and operation of this valuable national asset by a private-sector, commercial space partner will ensure its continued viability and allow for its continued use in support of U.S. space activities," NASA said in a press release.

Negotiations will begin with SpaceX to lease pad 39A for at least five years. If successful, launches could start within a few years, marking a major turning point in KSC's effort to transform into a spaceport for both government and commercial operations.

The competition for the pad was often framed as a battle between billionaire entrepreneurs, with SpaceX led by PayPal co-founder Elon Musk and Blue Origin started by Amazon.com CEO Jeff Bezos.

Blue Origin has yet to fly a vehicle in space and won't have a rocket ready to use the pad until at least 2018, but had proposed operating 39A for multiple users, in contrast to SpaceX's request for exclusive use.

SpaceX rival United Launch Alliance supported Blue Origin's approach but did not commit to using the pad.

Members of Congress also weighed in, some opposing an exclusive lease and others - including the entire Florida delegation - saying NASA should be left alone to make the decision.

On Friday, Blue Origin President Rob Meyerson said the company hopes NASA "will preserve options to make this national asset available for multiple commercial users."

SpaceX said it would welcome other users with NASA-certified human launchers.

NASA says pad 39B, which the agency is preparing for launches of crews on its own heavy-lift exploration rocket, also will be available to commercial users.

The space agency did not immediately explain why it chose SpaceX.

SpaceX has nearly 50 launches under contract and operates pads at Cape Canaveral Air Force Station and Vandenberg Air Force Base in California.

SpaceX expects to launch so often in the coming years that it also wants to develop a private launch complex. Texas is said to be the front-runner, but Florida has proposed an alternative at the north end of KSC and the Merritt Island National Wildlife Refuge.

"It would be used to deal with missions if we're too busy out of the Cape, basically," Musk said last month in Cocoa Beach.